Colloquial term for a fellow human being who may be viewed as a best friend or mortal enemy depending on your level of intoxication. It is acceptable that both contexts of the word are used on the same person during the course of a night out.

How's it going brus? (Sit down, have a beer with me)
I love you brus (You're my best mate right now)
I'm gonna smash you brus! (You used to be my best mate but I'm about to knock you out with a few coonies to the head)